Liquid Injection Instrument Needle Safety Mechanism
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Solution Overview
Problem
Existing liquid injection instruments are prone to accidental punctures due to unintentional movement of the syringe unit after use and have complex structures that complicate operability, leading to user hesitation and fear during drug administration.
Innovation Solution
A liquid injection instrument with a simplified structure featuring a protector with U-shaped slits, an inside engagement piece with claws, and a plunger with inclined surfaces, which ensures the needle is safely retracted and prevents accidental punctures by engaging the outside engagement pieces, allowing for controlled operation without a button mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a syringe unit with a movable needle is used to allow needle retraction after use, then needle safety is improved, but the syringe unit may unintentionally move to the protruding position causing accidental punctures
Solution Approach 1:
The patent applies preliminary anti-action by providing a dedicated button that actively maintains the needle in the retracted position through engagement with the syringe unit. This preventive mechanism counteracts any forces that might cause unintentional needle protrusion before such an event can occur, rather than merely responding to accidental movements after they happen.
Solution Approach 2:
The patent introduces a button as an intermediary element between the user's hand and the syringe unit. This mediator provides secure engagement and control over the movable needle mechanism, preventing direct contact that could cause accidental punctures while maintaining safe operation of the injection device.
2Ease of operation
If a syringe button is added to control the movable syringe unit, then operability is improved, but the structure becomes complicated
Solution Approach 1:
The patent merges the button structure with the syringe unit housing, integrating the control mechanism into the existing device architecture. The button is positioned to engage directly with internal components of the syringe unit, eliminating the need for separate complex transmission mechanisms and reducing overall device complexity while maintaining ease of operation.
Data Source
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AI summary
A liquid injection instrument includes an internal structural body having a cylindrical body that has a cylindrical shape and has an inner cavity part in which a drug solution is housed, a hollow needle disposed at a distal part of the cylindrical body, a gasket slidable in the cylindrical body, and a plunger that carries out movement operation of the gasket along an axial direction of the cylindrical body. The liquid injection instrument further includes a cylindrical protector disposed on an outer circumferential side of the internal structural body movably along the axial direction of the internal structural body. The protector has an outside engagement piece and the cylindrical body has an inside engagement piece engageable with the outside engagement piece. When a distal opening of the protector moves to a position closer to a distal side than the needle tip of the hollow needle again after moving from the position closer to the distal side to a position closer to a proximal side than the needle tip, the outside engagement piece engages with the inside engagement piece, so that the distal opening is prohibited from moving to the position closer to the proximal side than the needle tip again.